I've just started a directory where I list out verified suppliers, wholesalers, dropshippers and white label companies for a subscription fee. What other services can I offer to add value + monetize the site?
@Paul is right. "How" if is unimportant unless you know "why". I built the largest local business directory in the US in 1996 that was then acquired in 2004.
The critical issue you face, that we faced, is being a trusted source of the information in your vertical because that generates traffic to the sellers who were there for buyers. The add on services we provided (a suite of about 20 supplementary products to support online commerce, ad integration with other platforms, marketing and sales support suites, among others) had no value if we did not have market credibility to the users. What we had was a known need for both sides of the market (in this case, for consumers needing local business information).
Directories do not succeed because of a plethora of sellers; they succeed because of a plethora of buyers. Adding seller functionality that buyers find of no value in is a bad approach. Adding services sellers have no use for is a bad approach.
You are asking the wrong questions to the wrong audience. Building products that I have no use for has taken down 90% of all startups. If you have done direct research with both sides of your market, the answers are already in your hand. If you have not, stop what you are doing and get this crucial step done. You may find you have no market, yet that is better to find now than in a year and thousands and thousands of dollars of investment are wasted.
The question of how to monetize has a lot to do with WHY you needed to create this directory in the first place? Why couldn't people find this information before? What is unique about the information? What details are you offering that are exclusive? What makes your directory an improvement over contacting these suppliers directly? Are you saving time, money, or effort?
Most importantly, what have customers been asking for that they could not get until you created this resource? That's what you can charge for.
Your direct research in validating your marketing strategy informs you what your customers will pay under which conditions for which services. It sounds like you may have launched without testing your strategy to know what your business should be.
Some thoughts - framed as questions since I don't know what your personal or team capabilities are. Can you offer personalized introductions to these vendors to people who want to start a dropshipping service? Do you have materials to show someone who wants to start a dropshipping service how to evaluate volume discounts, for example, or how to find their target customer? Can you offer qualified leads to the vendors? Can you promote certain vendors over others, or verify that people who subscribe to your directory are X% likely to start a company and have Y need in Z months? What other services can you offer the would-be founder, or the vendor salesperson, that create value for them?
In short, what you can do is determine: what are the million and one ways you can make life easier for the people involved in these transactions? Then put up some ads on your site and see what your customers are interested in buying.
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