… it reminds you to buy new silver product (7)

I believe the answer is:

nagware

'it reminds you to buy' is the definition.
(nagware nags you pay for software)

'new silver product' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'product' becomes 'ware' (someone's wares are the products they sell).
'n'+'ag'+'ware'='NAGWARE'

I've seen this clue in The Guardian.

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