While acquiring a company that owns trademarks either through registration and/or licensed use the documents reflecting the transaction will almost surely include representations by the seller as to what trademarks are being sold or the rights of use being transfered, and the state of the seller’s title in them.
Timely and thoughtful due diligence will help the acquirer avoid potentially expensive and time-consuming post-sale problems ranging from defective title in the marks, to unexpected claims by third parties seeking damages for the buyer’s use of the marks it believed it had acquired. The intensity and depth of the investigation will vary depending on the value of the trademarks, and in particular, on their significance to the business being acquired.
Seller’s would normally disclose in the pre-sale what marks it owns, and publicly available databases should contain this information. For Russia and Kazakhstan we use https://trademarkbase.ru database.
Here is an example of trademark due-diligence: